1. Field of the Invention
The present invention relates to a slurry hydroconversion process conducted in two hydroconversion stages wherein the temperature of the second stage is at least 10.degree. F. higher than the first stage.
2. Description of Information Disclosures
Slurry hydroconversion processes in which a catalyst is dispersed in a hydrocarbonaceous oil to convert the oil in the presence of hydrogen are known.
U.S. Pat. No. 4,134,825 discloses a catalytic slurry hydroconversion process using a catalyst produced in the oil feed from a catalyst precursor.
U.S. Pat. No. 4,151,070 discloses a staged hydroconversion process in which the liquid effluent of the first hydroconversion zone is separated into fractions and in which the heavy fraction is passed to a second hydroconversion zone. The first hydroconversion zone is operated at a lower temperature than the second hydroconversion zone.
U.S. Pat. No. 4,606,809 also discloses a staged hydroconversion process wherein the temperature of a second stage is higher than that of a first stage, except product is not removed between stages.
The exothermic nature of hydroconversion of heavy hydrocarbonaceous oils to lower boiling products is disclosed in U.S. Pat. No. 3,622,497 wherein the effluent from the reaction chamber is substantially higher in temperature than the inlet temperature of the chamber. The temperature gradient from inlet to outlet is maintained at a temperature less than about 450.degree. C.
The term "hydroconversion" is used herein to designate a process conducted in the presence of hydrogen in which at least a portion of the heavy constituents of the hydrocarbonaceous oil is converted to lower boiling hydrocarbon products while it may simultaneously reduce the concentration of nitrogenous compounds, sulfur compounds, and metallic contaminants.
It has now been found that adding the fresh oil feed to more than one hydroconversion zone of a plurality of serially connected hydroconversion zones wherein each subsequent zone is maintained at a temperature of at least 10.degree. F. higher than the preceeding zone, will provide advantages, such as a decrease in hydrogen preheat and a decrease in overall catalyst requirement. Furthermore, the use of more than one hydroconversion zones, as well as the introduction of fresh feed into more than one hydroconversion zones contributes to the control of the exothermic reaction taking place in said zones.